Antacid suspensions are standard medications for the treatment of heartburn and other gastrointestinal disorders. Antacids neutralize the gastric acids created in the stomach. It is desirable that an antacid feature a high acid neutralization capacity and a rapid rate of gastric acid neutralization.
Antacids are available in the form of liquid suspensions or solid dosage forms. Liquid dosage forms are usually preferred over solid (tablets) because of their rapid action. Liquid antacid compositions are useful in the treatment of acute and chronic upper gastrointestinal disorders. The liquid antacids are usually indicated for the symptomatic relief of upset stomach associated with the hyperacidity also know as heartburn, acid indigestion and sour stomach.
A disadvantage associated with antacids in general (both liquid and solid forms) is an undesirable chalky taste. This can cause problems with patient compliance since patients tend not to use medications which are palatable. This is a disadvantage associated with antacids which are taken frequently for chronic treatment.
It is known in the art that conventional milling or homogenizing of antacid suspensions can alleviate the chalkiness to some degree but not entirely. For example, U.S. Pat. No. 4,533,543 (Morris et al.) describes improving the texture of solid antacid formulations by maintaining a small particle size, e.g. less than 500 millimicrons, and coating the particles with a mixture comprised of a fatty material or oil. U.S. Pat. No. 3,843,778 (Diamond) also discloses coating solid antacid particles, ranging in size from 0.05 to 300 microns, with an oil to create an improved texture.
Further, it is known in the art to use linear polyols, such as mannitol and sorbitol, specifically with aluminum hydroxide gels, to inhibit the polymerization reaction that occurs on aging. Shah et al., 70 J. Pharm. Sci. 1101-1104 (October 1981) teaches that polyols have a negative effect by reducing the rate of acid neutralization. Shah discloses that by carefully selecting the specific polyol and concentration, gel stabilization can be optimized.
Dihydroxyaluminum sodium carbonate (DASC) is a widely used gastric antacid. It has the formula (HO).sub.2 AlOCO.sub.2 Na and is typically prepared by a batch process in which aluminum isopropylate (i.e. aluminum isopropoxide) is contacted with an aqueous solution of sodium bicarbonate, see e.g. U.S. Pat. No. 2,783,179. Other methods of manufacture are known, see e.g. U.S. Pat. No. 4,438,085.
There is a need in the art to provide a liquid antacid composition containing DASC that is non-chalky and translucent in appearance. Translucency appeals to the patient/user because it connotes purity and good mouth feel, as opposed to the chalky, granular taste normally associated with liquid antacids.